Former Conservative Defence Secretary Liam Fox has hit out at the pro-Union campaign in last year's independence referendum.
The Tory MP accused Better Together of failing to make a positive case for the UK.
He suggested that the same mistakes must not be repeated in any second vote.
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And he urged on the pro-UK side to "start today" and begin setting out why Scots benefit from rejecting independence.
He was speaking during a fringe at the Conservative party conference in Manchester.
He was pressed on the issue a Tory activist who accused David Cameron of a "cack-handed" response to the independence result.
The Prime Minister has faced criticism for announcing plans to restrict Scottish MPs voting rights just hours after Scotland voted to remain in the UK.
Mr Fox said: "I think there was a major, major problem with the Better Together campaign.
“That was that it was not talking to the right audience, because it kept saying why the Union was better having Scotland in it.
“Which was not what Scots were interested in.
“They wanted to know why they would be better off being in the Union.
“And we have to start making that case. That it is about the people of Scotland, not about being in the institution of a Union. “
He added that events in the last year had made the case stronger.
“We got to say to people in Scotland ‘you are better off being in the Union. Because had you voted last year for independence with oil prices plummeted you would find yourself in quite a pickle...’
“You have got to tell Scots why it is good for them. It was all very nice for us to enjoy why the Union was stronger having us Scots in it but that was not actually what the voters in Scotland were discussing or what they wanted to hear.
“So maybe next time - and maybe starting today - we might want to make the case in a positive way for why they benefit from being in the Union and not the other way round.”
He also called on America back a UK exit from an "unreformed EU".